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The article investigates an outbreak of a wilt like disease of alfalfa (lucerne) in the Markazi Province of Iran. Symptoms during early growth stages typically consisted of V-shaped orange-pinkish necrotic areas on the leaflets. On severely affected shoots of more mature plants, leaflets were usually desiccated and twisted, forming spirals. These symptoms are very similar to those reported for verticillium wilt in alfalfa sterilized stem tissue onto water agar. The fungus was confirmed as the causal agent of the disease by inoculating Lucerne plants by root dipping into conidial suspensions. This is the first reported occurrence of verticillium wilt disease of alfalfa in Iran, or indeed anywhere in continental Asia. This particular wilt can be a severe disease in alfalfa and, should it become widespread in Iran, it could cause significant crop loss.

SUMMARY Two of the currently widely accepted species in the section Nigrescentia of the genus Verticillium are major plant pathogens inducing wilt diseases in a wide range of mainly dicotyledonous hosts. Three species closely related to these two are less important wilt pathogens and soil saprophytes. A sixth species, V. theobromae, causes the cigar end of banana. Molecular and genetic studies have shown that these species represent a complex pool of discrete lineages of varying degrees of relatedness with unknown levels of gene flow between them. Most isolates are haploid, but some are thought to be amphihaploid interspecific hybrids. Until our understanding of this complex is much improved, it seems most appropriate to add only one new species, for wilt isolates primarily associated with potato and producing dark-resting-mycelium in bundles (currently known as V. albo-atrum Grp2). It is suggested that the following be retained: (i) V. dahliae to include all isolates which produce only microsclerotia, (ii) V. albo-atrum to cover the majority of isolates producing only dark-resting-mycelium (and not in bundles), and (iii) V. nigrescens, V. nubilum, V. tricorpus and V. theobromae for the minor wilt pathogens/saprophytes and the non-wilt pathogen.